The lysosomal membrane is rich in ___________.

(a) Sterols

(b) Cardiolipin

(c) Sialic acid

(d) All of the above

(c) Sialic acid

The inner side of the lysosomal membrane is heavily coated with sugar molecules (glycosylated), forming a protective layer called a glycocalyx. This layer is particularly rich in sialic acid.

This dense sugar coating is crucial for the lysosome's function, as it shields the membrane itself from being destroyed by the powerful digestive enzymes contained within the organelle. While other components like sterols are present, the high concentration of sialic acid is a defining and protective feature of the lysosomal membrane.